Fig. 9: Comparison of major surface processes on ancient and modern Mars.
From: Detection of ferrihydrite in Martian red dust records ancient cold and wet conditions on Mars
The left panel depicts ancient Mars during a period of active chemical weathering through hydration and oxidation of basaltic crust to produce ferrihydrite-rich waters. Meltwater runoff triggered by volcanic activity transported insoluble ferric iron into crater lakes and basins to form sedimentary deposits. The right panel shows modern Mars where continuous erosional processes rework sedimentary layers and distribute fine-grained material across the planet to create its characteristic ochre appearance. Schematic not to scale.
